This study examines the relationship between the occurrence of major transitions in the lives of children and their psychological adjustment. Children are studied in transition from elementary school to middle or junior high school and from childhood to early adolescence. Their adjustment in school before transition and their ability to withstand the stress of the changes they encounter during transition are examined in children's self-reports and reports from their teachers and peers. Analyses focus on (a) the range of psychological functioning in a normal volunteer sample of 445 children, (b) the incidence of vulnerability in terms of low self-esteem, poor self-image, isolation, and loneliness--factors implicated in the affective disorders leading to depression and suicide and in acting out behaviors that stabilize in mid-adolescence and peak in the 15- to 25-year age bracket.